EP1608899B1 - Piston ring - Google Patents

Description

The invention relates to a piston ring with a shock-forming slot, a tread, an inner peripheral surface and extending therebetween upper and lower edges, wherein in the region of the inner peripheral surface an inconsistent cross-sectional disturbance is provided, seen in the circumferential direction, formed larger in the region of the shock is as in the shock diametrically opposite area. Of the DE-C 39 20 449 a self-cocking gas-sealing piston ring is to be taken, which touches the groove flank of the piston in the mounted state with its upper flank center to inside. The lower edge is inclined relative to the groove flank so that it is also touched centrally to inside. In the inner peripheral region designed as a chamfer cross-sectional disturbance is provided.

In the US-A 2,591,920 a piston ring is described, which is provided in the region of its inner peripheral surface with differently shaped cross-sectional disturbances. By the JP-A 09196171 a piston ring for internal combustion engines has become known, which, seen over the circumference, has different wall thicknesses. Today's commercially available piston rings often provide a Vertwistung of the piston ring by a constant over the circumference of the piston ring cross-sectional disturbance (eg Innenfase or angle) before. This constant cross-sectional disturbance causes under the installation stress in the ring due to the piston ring theory, seen over the circumference, uneven Vertwistung of the piston ring.

The invention has the object of developing a generic piston ring to the effect that the piston ring rests in all phases without gas pressure load only with the lower tread edge on the cylinder wall and with the inner edge of the lower groove flank and at the same time contributes to improved oil consumption control.

This object is achieved in that the piston ring has a wall thickness which varies in the circumferential direction, wherein in the region of the impact, the wall thickness is formed smaller than in the impact diametrically opposite region, wherein the Relationship between wall thickness and cross-sectional disturbance is always formed so that the piston ring, seen over the circumference, has a constant twist angle. Advantageous developments of the subject invention can be found in the dependent claims.

With the changes or superpositions of piston ring wall thickness and inconstant cross-sectional disturbance, a piston ring transmission can now be brought about, which, viewed over the circumference of the piston ring, brings about a constant twist angle. With the subject invention, it is now possible that the piston ring rests only with the lower tread edge on the cylinder wall and with the inner edge on the lower groove flank. On the type of wall thickness change in connection with the respective cross-sectional disturbance different but over the circumference constant twist angle can be brought about.

By an inconstant over the circumference of the piston ring cross-sectional disturbance is achieved that the area moment of inertia over the circumference of the ring can be varied so that in turn sets a constant over the circumference Vertwistung the ring.

The cross-sectional disturbances can be formed both by an inner bevel and by an inner angle, wherein the same can be provided either in the region of the upper or in the region of the lower flank.

worin

• ϕ der Twistwinkel
• Mt die Biegebelastung
• G der Gleitmodul
• I das polare Flächenträgheitsmoment

sind.The ratio between wall thickness and cross-sectional disturbance should satisfy the following formula for realizing a twist angle which remains constant over the circumference of the piston ring: $$\mathrm{\phi }\mathrm{=}\mathrm{Mt}\mathrm{/}\mathrm{G}\mathrm{*}\mathrm{I}\left(\mathrm{\phi }\right)$$

wherein

• φ the twist angle
• Mt the bending load
• G is the sliding module
• I is the polar area moment of inertia

are.

Figur 1

Kolbenring mit inkonstanter Querschnittsstörung;

Figur 2 bis 4

Verschiedene Querschnitte durch den Kolbenring gemäß Figur 1;

Figur 5

Kolbenring gemäß Stand der Technik mit gleicher Wandstärke und gleichmäßiger Querschnittsstörung;

Figur 6

Auftragung der Twistwinkel gemäß Stand der Technik (Figur 5) sowie des erfindungsgemäßen Kolbenringes entsprechend Figur 1.

The subject invention is illustrated by means of an embodiment in the drawing and will be described as follows. Show it:

FIG. 1

Piston ring with inconsistent cross-sectional disturbance;

FIGS. 2 to 4

Different cross sections through the piston ring according to FIG. 1 ;

FIG. 5

Piston ring according to the prior art with the same wall thickness and uniform cross-sectional disturbance;

FIG. 6

Plotting the twist angle according to the prior art ( FIG. 5 ) and the piston ring according to the invention accordingly FIG. 1 ,

FIG. 1 shows a piston ring 1, which can be used for example in the first or second groove of a piston (not shown). The piston ring 1 is shown in plan view, so that only the running surface 2, the inner peripheral surface 3 and the upper edge 4 can be seen. In the formed by a slot shock 5, the piston ring 1 has a predetermined wall thickness. The wall thickness of the piston ring 1 changes, starting from the impact 5 (0 °) in the direction of the diametrically opposite region 6 (180 °), which forms the ring back. At the ring back 6, a wall thickness is given, which is formed thicker compared to the impact area-side material cross-section. In FIG. 1 It is shown that in the region of the upper flank 4, a cross-sectional disturbance 7 entering the inner circumferential surface 3 is introduced in the form of a chamfer. The chamfer 7 begins with the same size cross-section at the joint 5 and decreases towards the ring back 6 continuously in both circumferential directions. By this measure, a piston ring 1 is provided with constant over the circumference, ie constant, Twishuinkel.

The FIGS. 2 to 4 show different sections through the piston ring 1 according to FIG. 1 , starting from the joint 5 (0 °). FIG. 2 shows a section near the shock 5, approximately at 10 °. FIG. 3 shows a section through the ring 1 at about 90 °. FIG. 4 shows a section through the ring 1 at about 180 ° (ring back 6).

The cuts according to FIGS. 2 to 4 show the tread 2, the inner peripheral surface 3 and the chamfered cross-sectional disturbance 7, which enters from the inner circumferential surface 3 in the upper edge 4. The sections show that the chamfer 7 has its greatest extension at the butt 5 (FIG. Fig. 1 ) and has decreased in the direction of the ring spine 6. In this way, as seen in the circumferential direction, different angles α between the upper edge 4 and the inner circumferential surface 3 are formed.

In the FIGS. 1 to 4 are cross-sectional disturbances 7, addressed in the form of chamfers. However, the same can equally well be formed by angular cross-sections in inconstant execution.

FIG. 5 shows a prior art attributable piston ring 8, in vertwistetem, ie built-in, state. The piston ring 8 includes a continuous wall thickness and is provided with a constant in the circumferential direction Innenfase 9 as a cross-sectional disturbance.

The diagram according to FIG. 6 shows that the piston ring 8, starting from the shock (0 °), occupies different twist angle in the direction of the ring back. The constant cross-sectional disturbance causes constant radial wall thickness under the installation stress in the ring 8 due to the piston ring theory over the circumference uneven Vertwistung the piston ring 8. When piston rings 8 should actually be achieved that the ring in all phases without gas pressure loading with the same twist angle only with the lower Tread edge abuts the cylinder wall and the inner edge of the lower groove edge, but what - especially FIG. 6 can be seen - with an uneven Vertwistung seen in the circumferential direction, so can not be brought about optimally.

Only with piston rings 1, as in the FIGS. 1 to 4 an equalization of the twist angle, seen over the circumference, can be brought about, so that now in all phases of the ring 1, without gas pressure loading the desired effect can be realized at moreover improved oil consumption control.

Claims (7)

1. Piston ring with a slot forming a joint (5), a run surface (2), an inner peripheral surface (3) and, running in between, upper and lower flanks (4), wherein in the area of the inner peripheral surface (3) a non-constant cross-section disruption (7) is provided which, viewed in the peripheral direction, is formed larger in the area of the joint (5) than in the area (6) lying diametrically opposite the joint (5), characterised in that the piston ring has a wall thickness which varies in the peripheral direction, wherein in the area of the joint (5) the wall thickness is formed smaller than in the area (6) lying diametrically opposite the joint (5), wherein the ratio between wall thickness and cross-section disruption is always formed so that the piston ring, viewed over the periphery, has a constant twist angle (ϕ).
2. Piston ring according to claim 1, characterised in that the ratio between wall thickness and cross-section disruption is always formed so that for given resistance moments (Wt) and bending stresses (Mt) in the fitted state, viewed over the periphery, the constant twist angle (ϕ) fulfils the following formula: $$\mathrm{\varphi }\mathrm{=}\mathrm{Mt}\mathrm{/}\mathrm{G}\mathrm{*}\mathrm{I}\left(\mathrm{\varphi }\right)$$

   

   
   wherein

   ϕ = twist angle

   G = shear modulus

   I = polar geometric moment of inertia

   Mt = bending stress.
3. Piston ring according to claim 1 or 2, characterised in that the cross-section disruption (7) is formed by a chamfer.
4. Piston ring according to claim 3, characterised in that the chamfer (7) runs in the peripheral direction at an angle α, wherein angle α varies in the peripheral direction.
5. Piston ring according to claim 3, characterised in that the chamfer (7) in the peripheral direction runs at an angle α, wherein angle α is constant in the peripheral direction.
6. Piston ring according to claim 1 or 2, characterised in that the cross-section disruption is formed by an angular recess.
7. Piston ring according to any one of claims 1 to 6, characterised in that the cross-section disruption (7) is provided in the area of the upper or lower flank (4).

Images